[tex]\begin{gathered} 20.Area\text{ big rectangule = (2x+3)}\cdot(x) \\ Areabigrectangule=2x^2+3x \\ \\ \text{Area small rectangule = (3)}\cdot(x-2) \\ \text{Area small rectangule = 3x-6} \\ \\ no\text{ painted area= }Area\text{ big rectangule - Area small rectangule} \\ no\text{ painted area= }2x^2+3x-(\text{3x-6})\text{ } \\ no\text{ painted area= }2x^2+3x-3x+6 \\ no\text{ painted area= }2x^2+6 \\ \\ \cdot\text{The no painted area is }2x^2+6\cdot \\ \\ 16.\text{ } \\ -7x-9-\text{ (}-4x+7\text{)} \\ -7x-9+4x-7 \\ (-7x+4x)+(-9-7) \\ -3x-16 \\ \text{The }substraction\text{ is }-3x-16 \end{gathered}[/tex]